Heh. I guess I'm arguing intent vs retcon.

The /intent/ of the Promethean weapons is that they shoot beams of light generated from physical ammunition. The Promethean weapons in Halo 4 still do that, and a blurb in the Halo 4 visual guide does nothing to change that.

Indeed, as you pointed out above, Covenant weapons fire 'ionized particles', and yet require no additional ammunition. With five million more years of development, the best that the Forerunner can do is a break-action hand-fed shotgun.

So, yes, it is an improvement that Forerunner weapons no longer fire "Hard Light". But that was just the surface of their troubles.